This invention relates generally to package wrapping machines utilizing thin, stretchable film to wrap and display articles contained in trays and, more particularly, to apparatus for selecting appropriate lengths of film from a continuous film source to wrap packages of varying sizes.
A variety of film wrapping machines are known in the prior art. Two examples of such machines are illustrated in U.S. Pat. Nos. 3,662,513 and 3,967,433. Both of the film wrapping machines as disclosed in these two prior art patents utilize a fixed length of stretchable film to wrap all packages regardless of differences in the sizes of the packages to be wrapped. The use of a single length of film to wrap all packages accommodated by a film wrapping machine obviously wastes film and can potentially create bulky clumps of film on the smaller package sizes wrapped by such machines.
To overcome these problems, film wrapping machines have been designed which permit the selection of a variety of film lengths by the machines to accommodate varying sizes of packages. Some machines provide manual operator adjustment for changes between film lengths while others provide automatic adjustment based on sensed package size characteristics. However, known prior art machines utilize conventional mechanisms to select the film lengths drawn into the machine to wrap packages.
Thus, the need exists for an improved mechanism for selecting one of a variety of film lengths to be used in a film wrapping machine.